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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Posted on 5 April 2013 by Riduna

Over the next 50 years, global population is expected to rise by over 40%, from 7 billion at present to about 10 billion by 2065. If we pursue a “business as usual” approach to CO2 emissions, can we to feed such a massive increase in population? The answer appears to be an emphatic “No”. Even if anthropogenic CO2 emissions were reduced to zero by 2050 (unlikely) the only peaceful alternative to extensive malnutrition, starvation and food wars is to curb CO2and population growth.

Ongoing anthropogenic emissions have increased the concentration of CO2 in the atmosphere from ~280 ppm in 1750 to almost 396 ppm now and increased the volume absorbed by seawater. The rising level of CO2 in the atmosphere is producing global warming which in turn is causing climate change characterised by increasingly severe and frequent weather events. All of these developments have an effect on our ability to produce, store and distribute food. Some of those effects are beneficial - most are not.

Carbon Dioxide

Continued increase in the concentration of CO2 in the atmosphere is having two significant effects on food production. It results in:

Ocean acidification: CO2 entering the atmosphere is largely absorbed by seawater where it forms carbonic acid, reducing the natural alkalinity of the oceans. The rate at which ocean pH is now falling is estimated to be greater than at any time since the Paleocene-Eocene Thermal Maximum.

Calcifying plankton and corals are endangered by this change since increasing acidity dissolves their shells making it more difficult for juveniles to secrete and maintain robust protection. This greatly increases their vulnerability. Many types of fish depend on plankton as their main source of nourishment, consuming them in vast numbers - and on coral reefs for habitat. Their depletion threatens to disrupt the food-chain and significantly reduce fish stocks, a problem exacerbated by overfishing and other forms of ocean pollution.

The massive decline of calcifying plankton will result in major depletion of commercial fish stocks and growing scarcity, even their total loss to those who depend on them most. Millions of humans rely on fish as their main, often their only source of protein.

Plant fertilisation: Elevated CO2 in the atmosphere promotes growth of food crops, particularly the major grain crops (rice, wheat and maize) estimated to increase yields by ~13%, (page 45) significantly less than the expected 40% growth in global population. However, CO2 also stimulates the growth of weeds which compete with food crops for nutrients in the soil. This can be handled by increased use of herbicides, technology better targeting weeds, adding nutrients to the soil and growing crops in a stable climate. Where this occurs the result is likely to be increased crop yield, though possibly with lower nutritional content and higher production (fertilisation) costs putting upward pressure on the cost of food.

Global Warming

The effect of CO2 emissions on average global temperature is a more serious problem. It has resulted in a 0.8°C increase since 1750, most of it occurring in the last 50 years. CO2 emissions are now rising at such a rate that, unless reduced, it is likely average surface temperature will have risen by 2°C by 2050 and at least 3°C by 2100. Global Warming has four major effects on food production, storage and distribution:

1. Reduced crop yield: Raising the level of atmospheric CO2 causes global warming, the latter destabilising climate and reducing crop yield. By stimulating plant growth CO2 also increases demand for nutrients in the soil such as phosphate, potassium and nitrogen. Demand for phosphate is already rising at a time when its availability is contracting while rising soil temperature depletes nitrogen content in the forms which plants can utilise. The outcome: declining food production per capita accompanied by increasing production costs

Food crops have evolved, or been genetically engineered, to produce highest yields where soil and climate conditions are ideal and stable. can be increased by growing crops in the presence of higher atmospheric CO2 concentrations, but only if sufficient nutrients and moisture are available in the soil and temperature remains within limits appropriate for individual crops.

The World Bank Report (pages 44-45) shows that changes to those conditions, particularly temperature and moisture, results in significant decline in yields. While rice yields do not appear to be so severely affected by rising maximum temperature, they are significantly affected by rising minimum temperature brought about by global warming.

2. Loss of agricultural land: Global warming has produced dangerous feedbacks – loss of albedo and increased methane emissions – over which we have no control. This will accelerate future warming and melting of land based ice, particularly polar ice, producing sea level rise. Present indications are that average sea level will rise by at least 1 metre and possibly in excess of 2 metres by 2100, most of it likely to occur in the latter part of the century. Even a 1 metre rise would cause coastal erosion, flood all of the world’s largest river delta’s and in the event of a storm surge, flood and salinate coastal plains.

Warming enables the atmosphere to hold more water producing an increasing number of flood events, washing away top-soil, impairing soil fertility and damaging food crops. Arable land is also removed from agricultural use by urban sprawl (page 38) an effect worsened by projected population increase.

The loss of so much agricultural land, much of it in the most densely populated areas, reduces capacity to produce the food needed to sustain rapidly growing populations. This problem is likely to be worsened by the loss of land now used for grain crops or meat production becoming marginal or unusable for these purposes because of a warmer and more severe climate.

Claims that global warming will open-up land areas in northern Canada and Russia to grain and other food crop production are unlikely to occur, except at the margins. It seems unlikely that stable climate suitable for food crops is going to develop in high latitudes. Further, it can takes a long time for land to develop the biota and nutrients required by such crops. The land north of that currently cropped lacks infrastructure and much of it is affected by permafrost which is seasonally degrading but poorly drained, often producing waterlogged land quite unsuited for agricultural production.

3. Loss of irrigation capacity: Highest food crop yields are obtained by growing crops on irrigated land where moisture can be controlled and optimised. However, capacity to irrigate is dependent on sustainable controlled use of water held in storage and regularly replenished. Three sources of stored water are glaciers, aquifers and dams.

Global warming results in precipitation in the form of rain rather than snow and melting glaciers, most of which are now in retreat. The result is that water is plentiful in winter but in short supply from melting snowpack in spring and summer when it is most needed. This limits the size of crops which can be irrigated from melt water, as evidenced in the Central Valley of California where Sierra Nevada glaciers are all retreating and no longer able to provide the water required for agriculture and burgeoning urban populations.

To maintain agricultural output melt water must now be supplemented by aquifer pumping. However, the rate of pumping required to maintain agricultural output is unsustainable and the aquifer is shrinking. A similar situation exists in north-west India where, in order to maintain food production, it is now necessary to pump aquifers at unsustainable levels. Although there is scope for improved efficiency in the use of water, ultimately a contraction of food production in these areas seems likely.

4. Reduced food safety and storage: Once harvested, food crops must be rapidly delivered to markets if they have a short shelf-life. Grains (from which we obtain half our calorific intake) are stored in local and regional silos until purchased by and supplied to distributers and processers. Grain in silos is subject to loss by consumption and contamination by bacteria, insects and rodents, a problem likely to be exacerbated by a warming climate. Food safety is likely to be adversely affected, particularly in developing countries.

Even in the United States, boasting one of the best developed transport systems in the world, 25% of food produced is lost between harvest and table. Increasing damage to infrastructure due to severe climate events is unavoidable and likely to increase loss of food crops prior to delivery to urban centres.

Extreme Weather Events

Most food plants grow in climatic conditions which produce the best yields. They have developed to flourish in a stable, predictable climate. Plants can (like humans) tolerate changes to climatic conditions, provided they do not occur outside known ranges of temperature and moisture and provided that where such changes do occur, they are short-term.

However, an inevitable consequence of global warming is climate change characterised by severe climate including wind events, prolonged droughts, heat-waves and precipitation - either as rain or snow - with fewer cold extremes. The timing and spatial occurrence of these events is largely unpredictable and therefore not yet adequately included in models seeking to describe the effects of climate on food production.

What we do know is that increasingly severe climate events will occur with growing frequency as average temperatures continue to rise and these will adversely affect food production. Recent examples of this are to be seen in:

The Russian heat-wave of 2010 destroyed 25% of the wheat crop, forcing one of the world’s major grain producers to stop exports for a year. It also killed around 50,000 Russians.

The U.S drought of 2011/12/13 destroyed 20% of the maize crop, reducing yields of soya bean and wheat crops, with thousands of head of livestock lost, forcing up the price of grain and meat and reducing food exports.

Events similar to the above all have the effect of reducing food production and increasing its price on the world market. Extreme events are expected to become the norm and grow in severity this century, increasing the damage caused to food crops and, in the latter part of the century, producing scarcity and sharp price increases resulting in regional famine and loss of life.

Farm viability can be threatened by the inability of farmers to deliver product because of infrastructure loss. Recent examples of this are seen in road flooding preventing access to dairy farms for the collection of daily milk production. As a result thousands of litres of milk – for which the farmer is not paid - are thrown away because they can not be stored until roads access is restored.

Summary

Rapid rise in global population, predicted to be over 10 billion by 2065, with consequential increase in demand for food and water is likely to be accompanied by:

Depletion of fish stock due to acidification, ocean warming and over-fishing.

Regional shortages of potable water due to loss of shrinking of glaciers.

Loss of best agricultural land due to flooding, erosion and salination.

These problems will not occur with immediate severity but will become more marked over the next 87 years, such that well before 2100 demand for food is likely to far outstrip supply.

The socio-economic results will be dire, unless alternatives to business as usual are pursued globally and immediately. Even then, it is possible that mass starvation and loss of life in the latter half of this century will prove unavoidable.

Comments

The "10 billion by 2065"(pdf) projection appears to have been made by the U.S. Census Bureau under the Bush administration in 2004, based on 2002 data, in a report with zero mentions of climate change, and zero references to climate change publications. This leads to eyebrow raising predictions, like Chad being among the fastest growing nations on Earth through 2050, more than tripling its population, even as Lake Chad shrinks to a record minimum in the west and desertification creeps into the east.

Remember North Carolina's 2012 bill that would have required people to only use past trends to predict sea level rise? This Census Bureau report reminded me a lot of that.

So it'll be interesting to see what effects climate change predictions will have on the Census Bureau's next world population projection revision - assuming it doesn't ignore climate change this time. Surely projected birth and mortality rates should change, at least on a regional basis. Combined with migration triggered by climate change, I'd expect the distribution of population growth to be on a different track, and perhaps even the total population curve.

Not Everybody thinks we will have 10 billion humans: Jorgen Randers (Club of Rome) predicts a peak of 8 billion due to lower fertility in cities, see short introduction of his report to the club of Rome "2052, a global forecast for the next 40 years", picking up after 40 years of "Limits to Growth": http://www.clubofrome.org/?p=703 . Randers says, that this lower than generally assumed population will cause lower growth than expected and a push back of the more catastrophic climate change effects to the second half of the century (if nothing is changed, which is what he explicitly assumes after 40 years of environmental activity with limited success ...).

It is also interresting to view the three videos given a the Smithsonian institute for the 40 years of "Limits to Growth", with each of the three speakers (Meadows, Randers, Brown) giving a different priority to the three dangers from the "Limits to Growth": resource scarcity (Oil, ...), pollution (climate change), population (food, water, ..).

Concerning food storage, it is possible to store wheat and other grains for 10 to 30 years depending on the method.

One method is conventional cans (about gallon size and larger) in an oxygen free environment - nitrogen is used to replace the oxygen. So long as its stored, out of the heat, at room temperature it will last for 20-30 years. Brown rice will only keep for 10 years.

Abrupt changes in climate will give us a 'feast or famine' cycle where we'll be able to grow adequate amounts some years but suffer extensive loss on other years. The only way to alleviate that is to store large quantities of grains during the 'good' years to make up for the bad years.

Eliminating biofuel production will also give us a large safety margin.

Going vegetarian will help even more but it's not going to happen voluntarily.

Agnostic, you mention one impact of warming in the summary but don't expand on it any further; warming of the oceans. I have never actually seen an assessment of the negative impact on biological productivity in the oceans of increased water temperatures. Have you any references on that?

Jonas@2, thanks for the links. It awakens memories. I think Forrester's world dynamics model had an unusual first "public" appearance. So far as I know, the results of his "World 1" simulation model first appeared in Playboy magazine. Dennis Meadows presented a preliminary version of the "limits to growth" model at our institute. In 1971, I was invited to speak to the Ann Arbor chapter of the Sierra Club on these modeling efforts. I focused mostly on the Forrester model, with which I was intimately familiar, because the Meadows work had not yet been completed.

Donella H. Meadows article "System dynamics meets the press" might have some useful suggestions for those interested in improving the communication of climate change and global warming issues to the public.

Decades ago, I got past my denial about global warming. Just a quick review of the science is all it took.

But now it's avoidance. I really don't want to examine this kind of problem, I see that it is inevitable and UN-avoidable - yet, like so many others who get the science - we really don't want to face consequences. Perhaps that's why we are drawn in to arguing about scientific methodology.

Sorry, looks like I haven't kept up to date on that story. The bill, in amended form, was passed into law on August 1, 2012. As amended, it no longer forces the state coastal agency to predict sea level rise based only on past trends. Instead, it prevents the state from predicting sea level rise altogether, until July 1, 2016, and requires the state to study the costs and benefits of the sea level rise regulations which, until 2016, it's not allowed to make. Until 2016, local officials can approve coastal developments using any predictions they like.

There are 3 billion people getting 60% of their protein from the oceans which will be depleted between 2035 and 50. Aquifer depletion circa 2040 will vastly reduce yields, -83% in affected areas. Soil salination from river water irrigation will also take out a good chunk as will soil micronutrient depletion from lack of organics. Citification will take more land and so will desertification. Then high priced oil and petro chemicals will affect prices, yields, and distribution, while its AGW will increase losses to crop failures from a number of reasons by climate fluctuation beyond historic. Adding them all up we get a realistic figure of being only able to feed between 3 and 4.5 billion just before 2050. An increasing death rate from a poor world economy will slow down population gain and by mid century it will be crashing geometrically while AGW increases exponentially. Then in 3-500 years it will really get worse. AETM and the finish of the Sixth Great Extinction. Preventable in the 20th century to very early this century. With nothing really sufficient being implemented, humanity is probably out of time to stop the Juggernaut of Ecocide.

Moguitar7 I can't follow your reasoning. If as you say, the population "will be crashing geometrically while AGW increases exponentially" what will be driving this exponentional increase in AGW? Presumambly not CO2 as levels surely will be falling geomentrically in line with the geometric crashing of the population.

I'm not sure I agree with all of Moguitar7 argument but what would crash with any crashing of population levels would be the rate of CO2 emissions, not CO2 levels. Any decline in CO2 levels requires first a major drop in the rate of CO2 emissions and then the time needed for the chemistry of the Carbon Cycle to then draw down CO2 levels. A part of that will happen within years to decades due to equlibration with the ocean. After that we are looking at centuries to millenia for other geo-chemical processes to sequester remaining CO2.

If natural feedbacks in the Carbon cycle occur due to higher temperatures - permafrost melt which has already started, destruction of some of the major carbon sinks in the form of rainforests, etc - then the starting point before any slow drawdown begins may be much higher than current CO2 levels.

but what would crash with any crashing of population levels would be the rate of CO2 emissions

Doesn't this assume that the crash in population levels would happen in the developed world ? (which produces most of the CO2 emissions). Surely food security issues are faced by the subsection of the world population that produce practically zero net emissions. Which, of course, makes Rays point @13 even less correct.

If what you say is correct then stabilising CO2 levels at say 400ppm, which is what it is suggested could help ameliorate if not avert AGW makes no sense. According to your arguments it seems that AGW will increase in the presence of a stable CO2 level. The IPCC have given the half life of CO2 at around 5-50 years. so presumably levels would graudally fall. And Glen why would the poulation of the developed world crash rather than that of the developing world? For a start the population of the developed world is less than that of the developing world and the developed world has more resources on which to call than does the developing world. Look at the current situation where the developed world is often asked to provide food aid to the developing world. It certainly isn't the other way round.so your argument seems to fly in the face of reality

Hi, what about increased desertification for your list of impacts resulting in lower yields?

Did I read somewhere (a while back) that a warmer world will lead to increased evaporation from soils? If so, then our industrial agricultural, which results in dead soils, is going to lead to significant erosion and desertification, even in developed countries.

I'm under the impression tthat organic and biodynamic methods could help buffer this because these methods produce living soils that can hold more moisture and can better adapt to changing conditions. I've seen studies that show equivialant yields from both methods with fruits and vegetables, but I'm not sure that these methods are sufficient for larger grain and maize crops.

Apologies Glen and Phil for not stating this earlier, Moguitar7 specifies AGW which as far as I know specifically means anthropogenic global warming. So if the anthropogenic component is diminishing geometrically as Moguitar7 asserts and which part of the population is diminishing is not specified, what component is causing an exponential rise in AGW? Surely in the face of a rapid decline in population CO2 levels would stabilise even if not fall, so, as Moguitar 7 asserts what would cause an exponential rise, not just a rise, in AGW? Surely it must be something other than the anthropogenic component.

The Greenhouse effect is approximately proportionate with CO2 concentration. Stablise the level of CO2 in the atmosphere and the GHE stablises too, at the new global temperature. This stablisation doesn't happen immeadiately due to thermal inertia (so whenever we do eventually stabilise CO2 levels, there will be a bit more "warming in the pipeline")

The lower the level we stabilise on, the less disruption to civilisation and the natural world.

As Glenn states, reverting to pre-industrial CO2 levels (and hence a climate similar to the last few thousand years) will take in the order of 1000 years. At least we are not aware of any natural process that will rapidly draw CO2 out of atmosphere.

I cannot read Moguitar7's mind, my view is broadly with Glenn's assertion that a decreasing population would, at best, stabilise CO2 levels. The proviso I mentioned @15 does suggest a mechanism by which population decreases whilst anthropogenic emissions continue.

Note that for CO2 levels to rise, you only need net CO2 emission to continue, if the amount of CO2 emitted year-on-year decreases, CO2 levels are still rising; you only stabilise CO2 levels when the anthropogenic contribution is zero (in other words the CO2 from last year doesn't disappear)

Even if CO2 levels even out or drop what about the delayed warmth "in the pipeline". I understand that is supposed to be 1F in the next 30 years.

Also, if industries stop consuming energy in large amounts then the sulfur emissions will drop. Those emissions reflect light therefore there will be even more warming. I understand that would be over 1F.

Steve Easterbrook summarized a recent lecture by Damon Matthews on the consequences of reductions of emissions. (Hat tip to somebody in some comment here on SkS a while ago who brought this up, but I dunno who.)

Jonas @ 3 … Thanks for the reference on population which shows a mid-range estimate of 9.3 billion by 2050, not inconsistent with an estimate of 10 billion by 2065. Even if we assume global population does not exceed 9 billion by 2100 (unlikely), can we assume that they will all be adequately fed and housed? Can human ingenuity in the sphere of genetics produce food plants able to cope with a rapidly changing, less predictable and more extreme climate?

Villabolo @ 5 … That’s a novel idea, canned wheat – very expensive but not very practical since it would involve transporting grain to a “cannery” The problem is how to store millions of tonnes of various grains to cover shortages arising from crop losses caused by severe climate events, grain losses due to insect and rodent predation and transport delay due to infrastructure damage. This already cause significant grain losses but nowhere near as large as those likely to occur as the effects of global warming increase.

Ivoryorange @ 17 … Good point. Desertification could well result from global warming induced climate change, such as persistent drought. I have not read much on this topic and I am surprised that very little on the subject is available on SkS. Both need rectifying.

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Moderator Response:

[DB] Desertification is an emergent outcome of a warming world, as is an intensification of the hydrological cycle. For the former, see this post. IIRC, Rob Painting has a forthcoming post on the latter.

Glen Tamblyn @ 7 … The most obvious effects of ocean warming are on fish habitat (eg coral reefs) and fish physiology – forcing fish to move further north or south of the equator, which is why I gave it a mention. It also leads to accelerated melting of ice, reduced albedo, rising sea levels, loss of permafrost, carbon emissions and a whole host of nasties not considered here.

Ainsworth et al (2011) point to the effects on biodiversity of ocean warming in their regional study of the NW Pacific. Pratchett et al (2011) also have some interesting stuff on the effects of ocean warming on seaweed and fish habitat and heaps of references to other material.

"Observations show that the Hadley cell has widened by about 2°–5° since 1979. This widening and the concomitant poleward displacement of the subtropical dry zones may be accompanied by large-scale drying near 30°N and 30°S. Such drying poses a risk to inhabitants of these regions who are accustomed to established rainfall patterns."

"The land area surrounding the Mediterranean Sea has experienced 10 of the 12 driest winters since 1902 in just the last 20 years. A change in wintertime Mediterranean precipitation toward drier conditions has likely occurred over 1902–2010 whose magnitude cannot be reconciled with internal variability alone. Anthropogenic greenhouse gas and aerosol forcing are key attributable factors for this increased drying, though the external signal explains only half of the drying magnitude. Furthermore, sea surface temperature (SST) forcing during 1902–2010 likely played an important role in the observed Mediterranean drying, and the externally forced drying signal likely also occurs through an SST change signal."

I was going to say it, but I say it so often I get tired, but yes, I think that Hadley Cell expansion, in and of itself, is one of the major expressions of climate change, and perhaps the one with the greatest human impact.

Hadley cell expansion means the desertification of otherwise heavily populated and mostly arable land. Most of the deserts of the world are defined by their position within the Hadley cells (the Mojave, Arabian, Sahara, all of the Australian deserts, etc.). But they are often bounded by heavily populated and farmed regions.

The expansion of the Hadley Cells will mean the desertification of otherwise useful land in Texas, Oklahoma, Spain, Italy and many other parts of the world.

Imagine a world where southern, or even all of, Spain and Italy are deserts. Imagine refugees leaving Texas and Oklahoma for "greener pastures."

Agnostic @ 23: Randers says: "The global population will peak around 8 billion people in 2040", see ca. 10:40, link to video starts at 9:50: http://www.youtube.com/watch?feature=player_detailpage&v=8qDy0jHo_DQ#t=590s I know this is not mainstream and I can't judge it, but it's interesting and it's a report to the club of Rome ... . See also http://www.2052.info , where you can also find the spreadsheet with the data to run your own forecasts, depending on the parameters. Just FYI.

The effect of extreme weather events in the context of food production scares me. If our population will be over 10 billion by the year 2065, how is it possible to shy away from industrial produced agriculture? The prices will sky rocket with drought looming ahead. How can sustainable food growth make its way back into the market when there are so many people to feed, many of which go hungry every day. Population seems to be the largest causal factor, in my opinion, when it comes to climate change. As this post shows, we are already seeing droughts, floods, and heat waves decrease the stability of mass food production and infrastructure (which is seen to be essential in transportation of crops.)It is hard not to feel despair when information is presented to me like this. I try to feel empowered, because I am gifted with this knowledge and can pass it on to others who might not realize the many effects that climate change has on the security of our lives.

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